The invention relates to safety devices to be used with stair-climbing systems (also referred to as xe2x80x9cstair-climbersxe2x80x9d) for conveying equipment and goods, in particular wheelchairs with handicapped persons.
Two construction principles are widely known for stair-climbers used for conveying wheelchairs with handicapped persons in stairways. One construction principle uses crawler chassis. The crawlers are long enough for at least three stairs to be grasped at the same time. In this way, accidental tipping over of the wheelchair and the person is impossible, so that falls with resulting injuries or even deaths are ruled out. These stair-climbers have problems with narrow and curved stairways, however, due to the length and width of the crawler chassis.
The other construction principle uses numerous wheels that rotate not only around their own axle but at the same time around an axle shared by all wheels. Cf. DE-C 37 13 564 or DE-C 32 26 294. With these apparatuses, it is advantageous on the one hand that only rubber-tired wheels come into contact with the stairway and, in particular, the stair edge, in such a way that damage is largely ruled out; on the other hand, it is quite dangerous that the wheels can only engage the steps to a limited depth. Operating these devices therefore requires particular caution and circumspection, namely not the least because the load is a human being. In actual fact, however, stairways have many different designs: they range from relatively flat stairways running completely straight to narrow, steep, winding staircases. Climbing the stairs with the stair-climbers based on the multiple-wheel principle is not without danger because the apparatus can tilt. The stair-climber, the wheelchair and the person must therefore be held by a strong operator. Unfortunately, accidents still take place repeatedly.
The present invention is based on the technical problem of indicating safety devices to add on to stair-climbing systems in danger of tilting over.
This technical problem is solved by safety devices.
These safety devices, for which there are the designs and further developments defined, have numerous advantages.
A first advantage quite substantial for the interested parties is that they can be added on to all known stair-climbing systems, including stair-climbers for conveying wheelchairs with handicapped persons, and those yet to be developed, in such a way that falls will no longer be possible in the future.
A further advantage is that the support arm can be constructed relatively short, because it only needs to bridge over one to two stairs. Since it is also very narrow, tightly winding stairways do not pose any problems either.
As a third advantage, it should be cited that the support arms according to the invention do not in any way change the handling of the stair-climber system itself, because in the normal situation, they are fully movable relative to the stair-climber system. Only when the stair-climber system assumes a position where there is danger of tilting over is the hinge of the support arm blocked, namely until the operator has brought the stair-climber system back into a safe position.
According to a first, preferred design of the invention, devices mounted in the lower end area of the support arm and preferably made of an elastic and thus stairway-protecting material bring about a support action impacting largely vertically on the stepping surface of the next step down and the step below that. It has been shown that the support on the stepping surface of the stairs is much safer and more reliable than a support at the front edge of the steps. The jolt caused when the hinge is blocked is optimally intercepted.
At the free end of the support arm, numerous of support feet are preferably mounted or molded on, one of which supports itself on the stepping surface of the next step down or the step below that in case of danger, as already mentioned. The arrangement of several support feet makes possible an optimal adaptation to different heights and depths of the stairs.
According to a further development, the support feet are divided into two units. One unit, preferably the upper one, is mounted sliding and pivoting on the support arm against a spring and is equipped with a blocking system that blocks the movable unit as soon as the force brought to bear on the stairway overcomes the force of the spring, which is always the case when the stair-climber is in danger of falling over the stairway and the braking and blocking system has blocked the hinge of the support arm.
In particular in order to protect the stair edges, according to an advantageous further development of this invention it is recommended to mount a runner parallel to the support arm, wherein a draw spring pulls the support arm into the runner in such a way that in the normal situation, only the front edge of the runner rests on the stair edges. It is understood that the spring force must be measured in such a way that in case of danger, the support feet of the support arm can deploy their support function without delay.
The runner preferably has a U-shaped cross-section. In this way, in the normal situation the support arm and its support feet are covered on all sides.
In order to protect the stair edges, the front edge of the runner can be coated with an easily sliding material. An even better protection results when a continuous belt is mounted in front of the front edge of the runner.
As was already mentioned, the hinge of the support arm must be blocked as immediately as possible as soon as the stair-climber leans dangerously forward and threatens to fall down the stairway. That means that the angle of the stair-climber must always be measured and monitored.
For this purpose, a heeling sensor is preferably used, in the form of a pendulum mounted on the stair-climber or on the mounting system.
Several variants are possible for the system for blocking the hinge.
According to a first variant, the braking and blocking system consists of a ratchet wheel and a ratchet. In this connection, the center of the ratchet wheel is preferably situated in the center of the axis of rotation. The ratchet is designed as a pendulum and mounted swinging around its own axis on the mounting system. As soon as the stair-climber tips forward, the ratchet engages the teeth of the ratchet wheel and blocks the hinge. Such a blocking system is mechanically simple and functionally reliable.
According to a variant thereof, the center of the ratchet wheel is offset relative to the axis of rotation. The ratchet is mounted swiveling around its own axis on the mounting system and is held in its home position defined by a spring between the ratchet and the mounting system. This variant of construction has the advantage that the ratchet does not have to adjust itself due to gravity, thus allowing greater freedom in construction. Also, the function corresponds to that of the first variant.
In both variants, the ratchet advantageously consists of a low-mass part that quickly engages the ratchet wheel due to its low mass, and a high-mass part that is responsible for maintaining the vertical direction. Both parts are drawn together by a spring that is weak enough, however, that the ratchet""s rapid engaging of the ratchet wheel is not delayed.
In both forms of construction, the angle of the ratchet wheel relative to the support arm is advantageously adjustable. In this way, shifting of the overall center of gravity, caused by different dimensions and weights of the stair-climber, the wheelchair and the handicapped person, can be compensated.
An alternative form of construction for the braking and blocking system is a lockable tension bar of finite length between the support arm and the mounting system or stair-climber.
A shoe brake can also be used as an alternative to this.
A spring band belt brake is preferred, because it works very quickly and reliably and has the necessary free-wheeling function.
As an alternative, an electric coupling can also be used.
According to a further variant, the braking and blocking system is designed as a lockable cylinder piston unit. These are preferably cylinder piston units with an internal fluid circuit and a check valvexe2x80x94controlled by the heeling sensorxe2x80x94in the fluid circuit. Hydraulic oils as well as gases come into consideration as the fluid.
According to an advantageous further development of the invention, there is a support spring between the support arm and the mounting plate. This support spring must be designed in such a way that it is powerless when the stair-climber system is in the properly inclined position relative to the stairway. If the stair-climber leans backward toward the stairway, the spring presses it back into the normal position. If the stair-climber is tending to tilt dangerously forward, the spring pulls it back into the proper position. In both cases, the support spring thus relieves the operator in terms of strength.
If the support arm is equipped with a runner, the springs between the support arm and the runner as well as between the support arm and the mounting system are to be coordinated in terms of force in such a way that if the stair-climber equipment leans dangerously down the stairs, the runner recedes and thereby releases the support feet to pose themselves on the stair.
To relieve the operator even more and also be able to convey heavy loads quickly and, above all, safely over the stairs, a drive is provided parallel to the braking and blocking system. This can be an electric motor with a screw thread, a hydraulic cylinder or the like. In any case, the drive is controlled dependent upon the difference between the desired position and actual position of the support arm relative to the stair-climber and/or the pressure force of the support arm on the stairway.
To support the support arm on the stepping surface of the stairs, not only support feet are suitable but also, for example, a continuous creeper band. Support wheels that are attached to a two-or three-arm turnstile are also suitable. Constructions of the turnstile and support wheels are already used in stair-climber systems. Lastly, there is even the possibility to equip the safety device with a power-driven drive that actively supports the lift mechanism of the stair-climber and is mounted on the support arm.
According to a first variant thereof, the creeper band or the turnstile with the support wheels can be driven by a motor. According to a second variant, a paternoster-type lift mechanism can also be provided on the support arm.
The lift mechanisms on the stair-climber and on the support arm are preferably synchronized with each other. In this case, the wheelchair is conveyed up and down the stairs with only minimal vibration. The operator has essentially only a guiding function then, and no longer a holding function. Such stair-climbers can thus also be operated by persons with less strength. However, the braking and blocking system remains active in these cases as well and in case of danger, prevents the stair-climber with the wheelchair and handicapped person from tipping over the stairway.